A new method will be used to investigate ion and water transport in the ciliary epithelium cells. A single ciliary process from a pigmented rabbit will be isolated, placed in a specially designed chamber, and rapidly perfused with physiological Ringer. Quantitative light microscopy will be used to measure the changes in the volume of a non-pigmented cell located at the edge of the ciliary process, when the perfusing solution is changed to solutions of different osmolality, composition, or temperature. A combination of volume measurements with the intracellular ion activity measurements will be used to estimate the water permeability of non-pigmented epithelial cells and the rate of transport of the major inorganic ions responsible for volume regulation and aqueous humor formation. The nature of the ion transport mechanisms will be further elucidated by the use of known inhibitors of transport in epithelia. Finally, we will investigate the effects on non-pigmented cells of the pharamcological agents used in the treatment of glaucoma.